Form bodies, such as briquettes, have been manufactured heretofore of a two-component mixture, whereby the first component comprises at least one fine grained solid material which does not soften below 800.degree. C. A second component comprises at least one pyrolytically decomposable binding material The mixture has a uniform or standard mixing and deformation temperature. However, the mean mixing and deformation temperature of the first component is above the standard temperature while the respective temperature of the second component is below the standard temperature. The standard or uniform mixing and deformation temperature of the mixture is such that a pyrolytic treatment and degassing of the mixture does not destroy the binding ability of the second component constituting a binding agent.
British Pat. Publication (GB) 2,157,312 B describes such a method wherein the deformable plastic mixture made of a first component comprising substantially thermally stable ingredients and a second component in the form of a pyrolytically decomposable coking hard coal, is treated in a travelling bed reactor which constantly subjects the mixture to a mixing and kneading motion. The travelling bed reactor conveys the mixture to a briquetting press which converts the mixture into form bodies by pressing. The briquetting takes place as a so-called hot briquetting and the so-produced form bodies containing coke and mixed cokes, already have a rigid, heat resistant skeleton of low temperature carbonization coke. If the temperature of the form bodies is maintained for a certain dwell time at the pressing temperature, the breaking and abrasion strength of the form bodies is increased to values which even surpass the strength values of normal lump coke produced by high temperature coking methods.
When briquettes or form bodies manufactured according to British Pat. Publication (GB) 2,157,312 B are burned, they leave an undesired ash component. This ash residue is due to the fact that the form bodies have been made by using coking hard coal as the binding agent or ingredient. Such an ash residue is especially disadvantageous if the form bodies, which have been produced with the aid of coking coal as a binder component and which contain in addition to the carbon, other ingredients such as quartz, heavy metal oxides, lime, and corresponding materials are to be used for the production of metals such as silicon or carbides, for example, calcium carbide in an electric furnace. For example, it is impossible to produce pure raw silicon by using sand and carbon containing form bodies which were produced by employing coking hard coal as the binder agent.
It is also known to manufacture form bodies of fine grained solid materials and of a binder agent in the form of liquified bituminous materials instead of the coking hard coal. Such liquified bituminous materials are defined in German Industrial Standards (DIN 55946).
The liquified bituminous materials are mixed with the fine grained solid materials and kneaded prior to their pressing. The mixing temperature, or rather the temperature at which the mixing takes place, is below the temperature at which the bituminous materials would thermally decompose. The mixing and kneading results in a deformable plastic mixture which is introduced into a briquetting apparatus for pressing the form or mold bodies. The so-produced form bodies do not leave an undesirable ash component. However, the so formed bodies lose their strength or rigidity when they are heated so that they require a gentle treatment during any further processing. Where it is necessary that these form bodies must have a sufficiently heat resistant coke skeleton, it is required to perform a follow-up coking treatment. Thus, it has been suggested that form bodies which are used as reduction agents in the production of metals or carbides, are subjected to the follow-up coking in the reduction furnace itself. However, this suggestion has not been found to be feasible in practice.